The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A nerve integrity monitoring (NIM) system can include a stimulation probe device, sensors, an electrode connection box, and an electromyography (EMG) monitoring device. The stimulation probe device is used to stimulate nerve and/or muscle activity. As an example, a stimulation probe device may include a stimulating electrode tip. A surgeon may touch a location on a patient with the electrode tip to provide a voltage and/or current to a location on the patient and stimulate nerve activity and as a result a muscle response (or muscle activity). A reference patch may be attached to the patient away from (i) the sensors, and (ii) an area being stimulated. An electrode of the reference patch can be at a reference potential. The sensors can include electrodes that are attached to the patient and used to monitor the muscle activity. A voltage potential between the electrode tip of the stimulation probe device and the reference patch and voltage potentials indicated by outputs of the sensors may be provided via wires to the electrode connection box. The wires are plugged into respective jacks in the electrode connection box.
The electrode connection box can have channels respectively for: a voltage potential of the stimulation probe device; a voltage potential of the reference patch; and output voltages of the sensors. The electrode connection box may filter signals received from the stimulation probe device and sensors and provide corresponding signals to the EMG monitoring device. Depending on the surgical procedure being performed, a large number of cables may be used to transmit information between (i) the stimulation probe device and sensors and (ii) the electrode connection box. As an example, 1-32 channels may be used during a surgical procedure. Each of the channels may correspond to a respective twisted pair cable (each cable having a twisted pair of wires). Each of the cables connected to the sensors is secured to a patient via the electrodes of the sensors, extends away from the patient, and is routed outside of a sterile field (or environment) in which the patient is located to the EMG monitoring device.
In one example, a certain type of sensor may be used during thyroid surgery to monitor nerves in intrinsic laryngeal musculature of a patient. Injury to a recurrent laryngeal nerve (RLN) is one of the most serious complications of thyroid surgery. An endotracheal tube can be used during thyroid surgery to open an airway and provide air to lungs of the patient. The endotracheal tube can include electrodes that are designed to contact vocal chords of the patient to facilitate EMG monitoring of the vocal chords during surgery.
As an example, a stimulating electrode may be placed on a vagus nerve in the neck of the patient to deliver continuous low-level stimulation to nerve endings. A baseline of nerve function is obtained and subsequent EMG responses are monitored via the electrodes connected to the endotracheal tube. Electromyographic signals are generated and detected by the electrodes and provided to an EMG monitoring device. The EMG monitoring device monitors changes in the electromyographic signals to detect changes in intrinsic laryngeal musculature of the patient. Between stimulations, nerves can be at risk due to surgical incision, and/or “blind” trauma caused by stretching, heating, compressing, and/or manipulating tissues of a patient during tumor/thyroid removal. The EMG responses are charted in real time to provide feedback with regard to the conditions of the nerves.